<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>01_JS的三种引入方式</title>
</head>
<body>
<button onclick="alert('请先登录')">点击即完</button>
<button onclick="console.log('点我干嘛')">点击即完2</button>

<h1 id="aaa">我是大标题</h1>
<script>
    console.log(aaa);
    console.log('我是内部写法');
</script>
<script src="01.js">
    console.log('测试了不会执行');
</script>>
</body>
</html>